The marvelous structure of the human brain has motivated many to make better use of its potential by becoming skilled at some trade, learning to play a musical instrument, mastering another language, or developing whatever talents add joy to life. “When you learn a new skill,” write Drs. R. and B. Bruun in their book The Human Body, “you are training your neurons to connect in a new way. . . . The more you use your brain, the more efficient it will become.”

Neurons in the higher region of your brain function like a video recorder. They can permanently store information that comes from your eyes and ears. Years later you can “play back” these sights and sounds, along with thoughts and other sensations that no man-made machine can record.